System and method for debugging a computing system

ABSTRACT

A system and method for debugging a development computing system is disclosed. The BIOS in the development system includes a debug engine. Interrupt-handling macros in BIOS include an entry macro to direct debug output codes (e.g., port 80 and beep codes) to the debug engine. A near entry macro is added to BIOS-segment macros (e.g., F000 segment) which provides the offset of the debug engine. A far entry macro is added to non-BIOS-segment macros which provides the segment and offset of the debug engine. The debug engine sends the output codes to a remote host computer via a communication channel (e.g., a bi-directional parallel port) on the development system. The debug engine also saves the contents of various registers on the development system to the host computer. Thus, the invention can be used in a stackelss environment. Debug commands (e.g., memory dump, set break address) can be issued from the host computer to the development system via the communications channel. Such commands are executed on the development system in accordance with program instructions in the debug engine. Debug data associated with the development system may be sent to the host computer via the communications channel in response to a debug command (e.g., memory dump data). Thus, a user can interactively and remotely debug the development system.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to debugging computer systems, and more particularly to a debugging engine that is resident in the hardware/software interface segment of memory on a development computing system and communicates debugging information to a remote host computer via a parallel port on the development system.

2. Background Art

BIOS Background

The architecture of most computers is generally defined by functional layers. The lowest layer is the hardware-the actual machine. The highest layer is the application program that interfaces with a user. In between the hardware and application program is the system software. The system software itself may be composed of several elements, including: the operating system kernel and shell, device drivers, and, perhaps, a multitasking supervisor.

Most architectures also include a low-level software layer between the hardware and the system software, called BIOS--Basic Input/Output System. The BIOS insulates the system and application software from the hardware by providing primitive I/O services and by handling interrupts issued by the computing system. Most computing systems are mainly controlled through the use of interrupts. Interrupts can be generated by the microprocessor, by the system hardware, or by software. The BIOS provides a logical handling of the interrupt signals. When an interrupt occurs, control of the computer is transferred to an interrupt vector which defines the "segment:offset" address of the routing in BIOS assigned to the given interrupt number.

BIOS Interrupt Service Routines (ISRs) handle interrupts issued by hardware devices. ISRs use registers in the microprocessor and BIOS data areas. The BIOS Device Service Routines (DSRs) handle software interrupts issued by the INT instruction.

The BIOS generally uses three data areas in RAM, including the Interrupt Vector Table, the BIOS Data Area, and the Extended BIOS Data Area (e.g., for power management). The BIOS also uses various input/output (I/O) ports.

BIOS Debugging

Debugging a computer system at the BIOS level is conventionally done with an in-circuit emulator (ICE). An ICE physically replaces the CPU in the development or target machine. The ICE is connected to the development machine through one buffer and with the host computer through another buffer. BIOS commands are received by the ICE through the buffers and processed by RAM resident in the ICE. The development computer BIOS accesses the ICE RAM exactly as if it was on the development machine. Attempts have been made to make ICE machines faster in order to handle debugging processing requirements. See for example, U.S. Pat. No. 4,674,089 (Poret, et al.) that discloses an improved very large scale integrated ICE that attaches to the motherboard.

ICE technology has many severe limitations. For example, ICE software is platform or CPU-specific and very expensive (around $50,000 per platform). An ICE tester is large and requires physical setup (removal of target CPU). This also necessitates a socket on the target machine for hookup. In addition, system specific ICE software may not be available when a new chip enters the market, thus ICE testing of development systems using the new chip are not possible.

Some modifications to minimize the amount of external circuitry required have been made in various debug peripherals or daughter boards. See, for example, U.S. Pat. No. 5,053,949 (Allison et al.) or U.S. Pat. No. 5,047,926 (Kuo, et at.). However, these systems still required a physical connection to the development machine CPU memory space, e.g., via CPU TAP, an internal CPU data bus connection, or ROM (read only memory) socket, and also require peripheral buffers.

Software debugging programs, such as Soft-ICE, allow for analysis of application-issued BIOS commands. However, these systems assume fully functional hardware, microprocessor, memory, stack, BIOS, and operating system on the development machine. Only BIOS commands to/from the application program are analyzed.

Limitations of the prior art reveal the need for a BIOS-level real-time debugger that is resident on the development system and does not require external circuitry for the debugging interface. It would also be desirable to have a low-cost, easily installed and accessible, low-level debugger capable of communicating debugging information to a remote host computer. Furthermore, it would be desirable to have such a system on a development machine that may not have RAM, a stack, a booted operating system, power management, or otherwise be fully functional.

SUMMARY OF THE INVENTION

A debug engine is resident in the BIOS segment of memory in a development system. Interrupt-handling macros direct debug codes issuing from the development system to the debug engine. The debug engine sends the codes to a remote host computer via a communication channel (e.g., a bi-directional parallel port) on the development system. The contents of various registers on the development system are saved on the host computer and later restored to the development system. Thus, the present invention can be used in a stackless environment. Debug commands can be issued from the host computer to the development system via the communications channel. Such commands are processed in accordance with program instructions in the debug engine. Data associated with the development system (e.g., memory dump) may be sent to the host computer via the communications channel in response to a debug command.

In one embodiment, BIOS-level macros (e.g., in segment F000) comprise a near entry macro that provides the offset of the debug engine in the BIOS. Non-BIOS-level macros comprise a far entry macro that provides the segment and offset of the debug engine. Debug codes are passed to the entry macros as parameters or by using a memory register (e.g., the AL memory register).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of the debugging invention.

FIG. 2 is a simplified block diagram of one embodiment of debug engine 112.

FIG. 3 is a flowchart of one embodiment of the interrupt-handling method of the debugging invention.

FIG. 4 is a continuation of FIG. 3 and is a flowchart of one embodiment of the debug command processing method of the debugging invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a block diagram of software and hardware tools for

implementing one embodiment of the present debugging invention 100. Debugging generally refers to, for example, error, fault, interrupt, or operation signal detection and/or monitoring, and/or the handling, diagnosing, or analyzing such information. Target or development system 102 is a computing system under development and is the subject of the debugging effort. Development system 102 may be a computer, a computer board, or other computing system or subsystem, and may comprise a processor 104, communications channel 106, and memory 108. Processor 104 may be a central processing unit (CPU) (e.g., Intel 80386, 80486, Pentium; Motorola 68020, 68030, RISC processor, SPARC processors and the like) or similar computer processing elements. Communications channel 106 is communicatively coupled to processor 104. Communications channel 106 may be a conventional communication port such as a bi-directional parallel or a serial port. Memory 108 is coupled to processor 104. Memory 108 may be conventional computer memory such ROM or RAM storage. In a preferred embodiment memory 108 is read only memory (ROM). Memory (or portions of memory) 108 may be fabricated into a silicon chip (e.g., a ROM chip).

Memory 108 comprises a low-level software system, interrupt-handling, or basic input/output system (BIOS), module, or portion 110 that communicates between hardware and software elements of development system 102. According to the present invention, BIOS 110 comprises debug module, program, means, or engine 112. As described in detail below, debug engine 112 facilitates the debugging of development system 102 by sending debug codes issued by development system 102 to host computer 118. Host computer 118 sends debug commands 120 to debug engine 112, which responds with appropriate action and/or sends debug data to host computer 118.

Development system 102 may also comprise additional memory or random access memory (RAM) 114 coupled to processor 104. Memory 114 may be conventional computer memory such as that provided by RAM on a computer chip, a RAM disk, and the like. Development system 102 may also comprise various other communications and/or input/output (I/O) ports 116. Port 116 may include a port for displaying debug codes (sometimes called"port 80" as is conventionally known in the art).

Development system 102 is communicatively coupled to host computer 118. Communication may be between a port 106 in development system 102 and a port in host computer 118 (not shown) with a conventional cable. Alternate modes of communication, such as fiber optic or infrared communications are also possible. In one embodiment, a bi-directional parallel port in host computer 118 is connected to a bi-directional parallel port 106 in development system 102 via a conventional DB 25 (25 pin) 8 channel straight through male to male parallel cable with the following modifications:

Pin 1 of side A connected to pin 11 of side B;

Pin 11 of side A connected to pin 1 of side B;

Pin 13 of side A connected to pin 14 of side B;

Pin 14 of side A connected to pin 13 of side B;

Pin 17 disconnected. Alternatively, a serial port in the host computer 118 is connected to a serial port 106 in the development system 102 via a conventional DB25/3 channel cable.

Host system, platform, or computer 118 may be any conventional computing system such as an IBM PC or compatible, a Macintosh, DEC, Sun or Hewlett-Packard workstation, and the like. Host computer 118 generally comprises a processor, monitor, keyboard, and/or mouse (not shown) for data input/output from/to a user. In the present invention, host computer 118 comprises debug software 120 and optionally user interface 122.

Debug software 120 provides conventional debugging tools and commands. Debug software 120 may depend on development system 102 being debugged and BIOS 110 running on development system 102. Typical command capabilities provided by debug software may comprise: memory dump, move memory data, modify memory content, trace, break address, replace debug code, exit process, go execute process, go to next debug code and stop, interrupt set, break address replace, disable break address (e.g., DR0 for Intel products), disassembly of the next instruction, initialize parallel port, dump registers, dump output of debug session to file, symbolic debugging, help, and the like. See, for example, the commands set forth in Appendix A which is attached thereto to form a part hereof.

User interface 122 provides, for example, display capability of data returned from development system 102, debug command entry, and other conventional user interface utilities such as windowing, text display, and graphics. This utility 122 may also serve as a general purpose hardware editor allowing the user to edit RAM, I/O ports, or registers, and the like.

FIG. 2 is a simplified block diagram illustrating BIOS 110 including debug engine 112. In one embodiment, debug engine 112 boot defaults are setup at memory location F000:E3f0H of PhoenixBIOS 1.03 (also called CBG103), and in the BCPS.INC file in PhoenixBIOS 4.0 (also called NuBIOS). See Tables I and II below. PhoneixBIOS 1.03 and PhoenixBIOS 4.0 are comercially available BIOS. Debug engine 112 facilitates the debugging of development system 102. Debug codes 205 are sent to host computer 118. Host computer 118 sends debug commands to debug engine 112, which executes the debug command on development system 102 and may send debug data to host computer 118. Debug engine 112 itself requires approximately 3K bytes in BIOS 110. A flowchart of the interrupt-handling and debug command processing of debug engine 112 is further detailed below with reference to FIGS. 3 and 4.

Conventionally, certain events or interrupts 201,208 during operation of development system 102 initiate macros, functions, or programs 203,209 in BIOS 110 that output information or codes 205 to a designated manufacturing diagnostics port. These events 201,208 may occur, for example, during the power-on-self-test (POST) of the development system, the providing of BIOS services, power management services, operating system startup, power management runtime services, and/or application software services. The designated diagnostics port 116 is generally port 080H, thus macros 203,209 are commonly referred to as port 80 macros and codes 205 are referred to as port 80 codes. See, for example, a list of port 80 codes as set forth in Appendix B which is attached hereto to form a part hereof. In addition,"beep codes" 205 are used to identify POST errors that occur when a monitor or screen is not available (e.g., not available or not functioning). See also Appendix B for example beep codes. Beep, status, warning, debug, port 80, interrupt, operating system, error, signal, diagnostic, and other similar information output from development system 102 are collectively referred to as "codes" 205. Normally, these codes 205 are not displayed. However, during development of development system 102, a diagnostic computer card can be inserted into a port 80 slot (116) to display the output codes 205. Such computer cards are conventionally known as diagnostic port 80 cards and are commercially available. As described above, certain ICE machines can also access some of these codes 205.

According to the present invention, BIOS-segment macro 203 (e.g., an interrupt-handling macro in segment F000) comprises near entry macro 207. Near entry macro 207 directs output code 205 to debug engine 112. From debug engine 112 code 205 can be sent to host 118 via communication channel 106. Near entry interrupts or events 201 only require an offset address to enter debug engine 112 (as opposed to a segment and offset) because they occur in the BIOS segment where debug engine 112 is normally located (e.g., F000segment). In one embodiment, near entry macro 207 is approximately 19 bytes. See Appendix C for a listing of example entry macros for PhoenixBIOS 1.03 and PhoneixBIOS 4.0

Similarly, various interrupts or events occurring in segments other than BIOS segment, or far entry events 208, also initiate interrupt-handling macros 209 that output codes 205. For example, power management, operating system (OS), video, application software interrupts, and other programs that do not reside in the BIOS segment may initiate interrupts that are handled by macros 209. Macro 209 comprises far entry macro 211 which also directs output code 205 to debug engine 112. Far entry macro 211 provides, among other things, the segment and address of debug engine 112 (e.g., F000:E3f0H in PhoenixBIOS 1.03). The size of far entry macro is approximately 44 bytes. Far entry macro 211 also comprises a reference to the segment it is used in. This enables debug engine 112 to return to the running program correctly after a debugging session. For example, to use the invention in a power management macro 209, far entry macro 211 should reference the segment that power management is running in. See Appendix C for a listing of example entry macros for PhoenixBIOS 1.03 and PhoneixBIOS 4.0

The function of near 207 and far 211 entry macros can be accomplished in one entry macro, however, memory is saved by providing separate entry macros for each type of macro. For example, one macro that provides to an interrupt macro 203/209 the segment:offset location of debug engine 112 in BIOS 110 and a reference to the macro it is used in could be constructed. Alternatively, a separate custom entry macro could be provided for each every macro 203,209.

Most CPUs have temporary storage registers (e.g., DR0 through DR7 in Itnel products). In one embodiment, near 207 and far 211 entry macros utilize various CPU debug registers for temporary storage (e.g., DR1 through DR3 registers). In one embodiment, if BIOS 100 is PhoneixBIOS 4.0 and debug engine 112 is not included in the BIOS segment, the contents of the debug registers (e.g., DR0-DR 7) will not be modified or destroyed. Thus, after debugging development system 102, debug engine 112 can be disabled (e.g., not linked into BIOS) without further effect on development system 102.

In one embodiment, code 205 is passed to entry macros 207, 211 as a parameter or by using a register (e.g., AL register). Both near 207 and far 211 entry macros can execute in stack or stackless environments. Also, in macros 203, 209, some "JMP short" (e.g., jump less than a set number of addresses) instructions might have to be changed to regular JMP instructions because of the additional address space occupied by the near 207 and far 211 entry macros.

If too many macros 203,209 (e.g., port 80 code display macros) have been modified to include entry macros 207, 211, BIOS 110 may be too large and build incorrectly (e.g., link and compile incorrectly). Several steps can be taken to alleviate this problem. For example, the unused features in BIOS or Power Management may be turned off to create more space, or the BIOS size may be made larger (e.g., modify Code Size and the ROM size in ROMOPT.INC file in PhoenixBIOS 1.03), or unused port 80 macros in the BIOS may be removed, or only the macros 203,209 for areas to be debugged (e.g., BIOS, Power Management, Video) may be modified to include entry macros 207, 211.

It is also possible to enter debug engine 112 via a break address set or DR0 interrupt 1 (213). When the address of the instruction being executed on development system 102 is equal to the address set in DR0, the break address, then a break entry into debug engine 112, defined by interrupt vector 1, will be made 213.

Debug engine 112 also comprises various debug command modules 217 that perform various debug commands such as memory dump, move memory data, modify memory content, trace break address, replace debug code, exit process, go execute process, go to next debug code, interrupt set, break address replace, disable DR0 break, and the like. Debug engine 112 receives debug commands form host computer 118 via communication channel 106 (e.g., bi-directional parallel port) and responds by executing command modules 217 and sending data, if requested, to host 118 via communication channel 106. Commands may be entered by a user through debug software 120 and/or user interface 122 running on host computer 118. Thus, the user is able to remotely and interactively debug development system 102 via communication channel 106. Debug mode or I/O mode 219 may be selectively set by the user to alter the communication of codes 205 to I/O port 116 (e.g., port 80) and/or communication channel 106. In one embodiment, BIOS 110 is PhoenixBIOS 1.03, and debug mode 219 may be set as follows: in the COMPAS.ASM file, the following lines as set forth in Table I are added before the SYNCA HRDDSRA hard disk DSR interrupt 13h:

                                      TABLE I                                      __________________________________________________________________________     SYNCA 0E3F0h         ;boot default for debug engine                            EXTRN debugEngineFarEntry:NEAR                                                                      :relocate debug engine                                    dw    debugEngineFarEntry                                                                           ;offset of the debug engine                               dw    0F000H         ;segment of the debug engine                              dw    0003H          ;UO or debug mode                                         dw    5A00H          ;break code default (00)                                  db    00,00          ;reserved                                                 PRGSIZA             ;display program size (reserved)                           where debug mode = DEBUG type, and default = 0003H                             Bit 0-3                                                                            0 DEBUG Off, codes not displayed on remote or on port 80H                      1 Port 80H, codes displayed on port 80H only                                   2 Parallel 1 (378H), codes displayed on remote and port 80H                    3 Parallel 2 (3BCH), codes displayed on remote adn port 80H                    4 Parallel 3 (278H), codes displayed on remote and port 80H                    5 Serial 1 (3F8H), codes are displayed on remote and port 80H                  6 Serial 2 (2F8H), codes are displayed on remote and port 80H              Bit 4                                                                              0 no delay for code display (default mode)                                     1 delay inserted for all debug codes                                       Bit 5                                                                              0 Reserved for debug engine                                                Bit 6-7                                                                            0                                                                          __________________________________________________________________________

In another embodiment, BIOS 110 is PhoenixBIOS 4.0, and debug mode 219 is set in the C:\NUBIOS\INCLUDE\BCPS.INC file, by setting values to variables as set forth in Table II according to the communication port 106 available on development system 102.

                                      TABLE II                                     __________________________________________________________________________      dbpDebugStruc STRUC                                                           Header bcpHeader.<`BCPDBG", 1.0,SIZEObcpDebug Struc>                           DEBUG.sub.-- OFF                                                                             EQU 0                                                                               ;DEBUG Off                                                  DEBUG.sub.-- PORT80                                                                          EQU 1                                                                               ;codes displayed on port 80H only                           DEBUG.sub.-- PARALLEL1                                                                       EQU 2                                                                               ;parallel port 1 (378h) and port 80H                        DEBUG.sub.-- PARALLEL2                                                                       EQU 3                                                                               ;parallel port 2 (3BCh) and port 80H                        DEBUG.sub.-- PARALLEL3                                                                       EQU 4                                                                               ;parallel port 3 (278h) and port 80H                        DEBUG.sub.-- SERIAL1                                                                         EQU 5                                                                               ;serial port 1 (3F8h) and port 80H                          DEBUG.sub.-- SERIAL2                                                                         EQU 6                                                                               ;serial port 2 (2F8h) and port 80H                          DEBUG.sub.-- DELAY                                                                           EQU 16                                                                              ;insert debug delay for debug codes                         debugMode     DW   ;bcpiDebugMode                                              debugBreakCode                                                                               DW   ;bcpiDebugBreakCode default                                 bcpDebugStruc ENDS                                                             bcpiDebugMode                                                                             =DEBUG.sub.-- PARALLEL1                                             bcpiDebugBreakCode= 05AFEH                                                                        ;05AFEH, 5AH is an identifier for                                              ;Debugging communication. The                                                  ;default Break Code is FE and can be                                           ;changed to any other value                                 __________________________________________________________________________

Then, add to the BCP.ASM file at the SAMPLES or OEM level to link the debug engine to the BIOS:

MAKE₋₋ BC P₋₋ DEBUG

INSTALL₋₋ DEBUG

When debug mode 219 is set to direct codes 205 to communication channel 106, the user needs to ensure that the communication channel chosen 106 is properly programmed and functional. One embodiment of debug engine 112 assumes that parallel port 106 always power up bi-directional, enabled, and set to port 3BCH. Most parallel ports are bi-directional parallel ports and usually default to bi-directional and enabled upon power up or reset. However, some development systems 102 may require the parallel port to be specifically enabled, assigned a certain address, and/or set to bi-directional after every power up or reset. If so, initialization code may be added to debug engine 112 prior to use. Parallel port base address can be modified to, for example, 3BCH, 378H, or 278H as specified above.

FIGS. 3 and 4 comprise a flowchart of one embodiment of the debugging method of the present invention. As described with reference to FIG. 2, depending on event 201,208, either near entry macro 207 (e.g, interrupts from segment F000H) or far entry macro 211 (e.g., interrupts from segments other than F000H) is used by macros 203,209, respectively, to enter debug engine 112. Unless all debug communication is disabled (e.g., debug mode 219 is 0 in Table I), code 205 is output 301 to port 80 or other designated diagnostics port. If communication to host computer 118 is not enabled 303 (e.g., debug mode 219 is 1 in Table I), a return 305 is made to the program running on development system 102 (e.g., at the next address). Another code 205 may then processed similarly. If communication to host computer is enabled 303 (e.g., debug mode 219 is not 0 or 1 in Table I), the contents of various registers in development system 102 are saved 307 on host computer 118 via communication channel 106 (see Table I or II for communication channel designation, for example). Because the development system 102 registers are saved on host computer 118, the present invention can be used in a stackless environment. Alternatively, development system registers can be pushed to a stack on development system 102, if available. A communication channel error check is made 309, and code 205 is sent 311 to host computer 118 via communication channel 106.

The method illustrated in the flowchart of FIG. 3 continues 311 in FIG. 4. After sending code 205 to host computer 118 (311 ), debug engine 112 determines 413 if a stop/wait flag is set, or if code 205 is a designated debug code (e.g., port 80 or beep code). If the determination at step 413 is "no", the contents of all registers are restored from host computer 118 via communication channel 106 (447) and a return to the program running on development system 102 may resume 449 (e.g., at the next address). Another code 205 may be processed similarly.

If the determination at step 413 is "yes" (e.g., stop/wait flag set or break code is equal to a designated break code), development system 102 stops executing and debug engine 112 awaits a debug command from host computer 118 via communication channel 106 (415). Depending on debug command 417 issued from host computer 118, debug engine 112 responds by executing the requested command 417 on development system 102. Conventional debug commands 417 may be issued to debug engine 112 as determined by, for example, debug software 120 running on host computer 118. See above in reference to debug 120 and Appendix A for a list of typical commands. Debug engine 112 comprises modules 419-443 (217) that, for example, execute the command 417 on development system 102, send data to host computer 118, and/or return to the running program.

For example, debug engine 112 may comprise the following modules in order to execute the corresponding command 417: exit process 419 or go execute process 421 (followed by exit process 419), will exit the debug engine process 447 and return to the next program process or return and execute the designated process 449; interrupt 1 vector set 423 sets a break address (set break entry point 213); break address replace 425, replaces the break address; disable DR0 break 427 disables the DR0 break interrupt; replace debug code 429 replaces the designated debug break code; memory dump 431 reads current memory storage, or a subset thereof (e.g., ROM 108 and/or RAM 114) and sends this information to host computer 118 (445); move memory data 433 moves memory in memory (e.g., RAM 114); trace 437, turns the tracer on and sends such data to host computer 118 (445); input from port 439 instructs debug engine to read data or an instruction from a designated I/O port; output to port 44 1 instructs debug engine to write to a designated I/O port. Other commands 417 may also be similarly implemented in corresponding modules 443.

Note, for the PhoenixBIOS 1.03 base code 110, when entering the power management SMI (system management interface) environment, debug engine 112 saves 307 and restores 447 the CPU debug registers (e.g., DR0 through DR7 for Intel products). Thus, if the user sets a break at an address (e.g., using DR0) 425 inside the SMI mode, this address may be overwritten when the registers are restored 447. Therefore, the save 307 and restore 447 routines of debug engine 112 may be removed to avoid overwriting.

When entering the SMI environment, the CPU 104 copies the content of the DR7 CPU register to SMRAM, clears the DR7 register and then restores its contents upon exit from SMI. This will disable the user specified break at an address feature 425 while in the SMI mode. Accordingly, the contents the DR7 register may be restored upon entry to the SMI environment from the SMRAM, or the break address command can be reactivated while inside the SMI.

Some parallel port cards may require substantial power to drive the input data to low (e.g., cards not designed according to conventional PS/2 bus standards). When such parallel port cards are used in conjunction with some notebook-type computers 112 which are designed to save power, development system 102 may not be able to drive parallel port data line 106. In this situation, a different parallel card (e.g., with lower power requirement), or a host computer 118 with a higher drive parallel port may be used.

During the initialization of development system 102 (e.g., during a POST), the operating system (e.g., DOS) may replace the interrupt vector 1 to its own interrupt vector. Therefore, interrupt vector 1 break addresses set 423 during POST and before DOS is initialized may not break at the address selected if the execution of the address happens after DOS boot. Break addresses set after DOS boot 423 will replace the interrupt vector 1 and will function correctly. Also, in order to break at an address specified by the user 423, the CPU requires stack space in memory 108. Thus, in a no-stack environment, alternate stack space is required in order to break at a specified address 423.

                                      APPENDIX A                                   __________________________________________________________________________     EXAMPLE DEBUG COMMANDS                                                         __________________________________________________________________________     AC[CESS]     Execute chipset I/O access utility                                B XXXX:XXXX or                                                                 B <Pattern>[+X(Hex)]                                                                        Add or replace the current break address with a new break                      address                                                                        or a Symbol                                                       BC           Turn OFF the break address                                        BO           Turn ON the break address                                         C            Clear the debug code that the user wants to break at              C ##         Replace the current debug code to a new debug code                CHIP[SET]    Execute chipset I/O access utility                                D XXXX:XXXX LENGTH                                                                           Default length is 128 bytes                                                   Dump memory location XXXX:XXXX to the screen, if the                           command line parameter switch /DTM is enabled then dump the                    data to 7000:0H on the remote computer also.                      DM XXXX:XXXX LENGTH                                                                           Default length is 128 bytes                                                  DM will not dump to the screen and will only save at                           7000:0H                                                           D <Pattern>[+X(Hex)]                                                                        Dump at first symbol that contains the "Pattern"                  DN           Dump at next symbol that contains the "Pattern"                   DOS          Exit this program temporarily and go to the DOS prompt                         The user can return to this program by typing EXIT at the                      DOS                                                                            prompt                                                            E XXXX:XXXX DATA                                                                            Enter data at memory location XXXX:XXXX                           F            Finds a given Symbol's value                                      FN           Finds the next symbol's value                                     G            Go to end, or stop at break address if debug register is                       set                                                               G XXXX:XXXX  Go to the specified break address and stop                        GN ##        Go to next or specified port 80h code or break address            H or ?       Help menu, will display this menu                                 I/IW/ID PORT Read from a 8/16/32 bit I/O port                                  L            Will load a new map file for Symbolic debugging                   M XXXX:XXXX LENGTH                                                                           Move a block of data from 7000:0 on the remote computer to                    specified memory on the development system. Length is the                      size of                                                                        transfer in bytes                                                 N            While break codes are being displayed this instruction will                    break at                                                                       the next break code. This instruction can be used when the                     debugger is not stopped at the command prompt                     O/OW/OD PORT DATA                                                                            Output data to 8/16/32 bit I/O port                              P            Continues execution and bypasses CALL, INT, LOOP, or REP                       instructions                                                      Q            Quit this program. Available at all times                         R            Display all the CPU register values and break code/address                     information                                                       R [REGISTER] [Value]                                                                         Modify the register specified (16/32 bit registers)              R flags      Will allow the lower 8 bit flags to be modified                   REGSON       Will cause the registers to be dumped with every T, G, P,                      and S                                                                          command.                                                          REGSOFF      Will cause the registers not to be dumped with every T, G,                     P, and                                                                         S command                                                         RESET        Will reset the development computer by issuing a hardware                      reset                                                                          via the keyboard controller                                       S            Sets breakpoint to the instruction following the current                       instruction                                                                    and then starts the execution. This is a useful command for                    JMPR                                                                           Macro bypass.                                                     T            Single step trace. This function can only be used after a                      break                                                                          address.                                                          U XXXX:XXXX LENGTH                                                                          Disassembles at memory location specified. Default is CS:IP       U <Pattern>[+X(hex)]                                                                         Disassembles at First symbol that contains the "pattern"                       specified.                                                       UN           Disassembles at next symbol that contains the "pattern"                        specified.                                                        __________________________________________________________________________      Break Address = Break Addresses are memory addresses that would generate       break instruction upon execution of code from that memory address and          would cause the Debug Engine to stop and wait for a response from the          remote computer.                                                               Display Code = Traditional Port 80H codes used for debugging.                  Break Code = Traditional Port 80H codes used to stop processing and revie      of registers/I/O/memory.                                                 

                                      APPENDIX B                                   __________________________________________________________________________     EXAMPLE DEBUG CODES USED IN VARIOUS BIOS                                       (PORT 80 AND BEEP CODES)                                                       __________________________________________________________________________     E.sub.-- REGS                                                                         EQU 01h                                                                               ; CPU register test in-progress                                  E.sub.-- CRAM                                                                         EQU 02h                                                                               ; 1-1-3 CMOS write/read test in-progress or failure              E.sub.-- BROM                                                                         EQU 03h                                                                               ; 1-1-4 BIOS ROM checksum in-progress or failure                 E.sub.-- TIMR                                                                         EQU 04h                                                                               ; 1-2-1 Programmable Interval Timer test in-progress or                        failure                                                          E.sub.-- DMAI                                                                         EQU 05h                                                                               ; 1-2-2 DMA initialization in-progress or failure                E.sub.-- PAGE                                                                         EQU 06h                                                                               ; 1-2-3 DMA page register write/read test in-progress or                       fail                                                             E.sub.-- REFR                                                                         EQU 08h                                                                               ; 1-3-1 RAM refresh verification in-progress or failure          E.sub.-- RAM0                                                                         EQU 09h                                                                               ; 1st 64K RAM test in-progress                                   E.sub.-- MMUL                                                                         EQU 0Ah                                                                               ; 1-3-3 1st 64K RAM chip or data line failure - multi-bit        E.sub.-- MOEL                                                                         EQU 0Bh                                                                               ; 1-3-4 1st 64K RAM odd/even logic failure                       E.sub.-- MADD                                                                         EQU 0Ch                                                                               ; 1-4-1 1st 64K RAM address line failure                         E.sub.-- RAMP                                                                         EQU 0Dh                                                                               ; 1-4-2 1st 64K RAM parity test in.sub.-- progress or                          failure                                                          IFDEF  RRREISA                                                                 E.sub.-- FSTIMR                                                                       EQU 0Eh                                                                               ; 1-4-3 fail-safe timer test in progress                         E.sub.-- NMIIO                                                                        EQU 0Fh                                                                               ; 1-4-4 software NMI port test in progress                       ENDIF  RRREISA                                                                 E.sub.-- MBIT                                                                         EQU 10h                                                                               ; 2-1-1 1st 64K RAM chip or data line failure - bit 0            ;          11h                                                                               ; 2-1-2 1st 64K RAM chip or data line failure - bit 1            ;          12h                                                                               ; 2-1-3 1st 64K RAM chip or data line failure - bit 2            ;          13h                                                                               ; 2-1-4 1st 64K RAM chip or data line failure - bit 3            ;          14h                                                                               ; 2-2-1 1st 64K RAM chip or data line failure - bit 4            ;          15h                                                                               ; 2-2-2 1st 64K RAM chip or data line failure - bit 5            ;          16h                                                                               ; 2-2-3 1st 64K RAM chip or data line failure - bit 6            ;          17h                                                                               ; 2-2-4 1st 64K RAM chip or data line failure - bit 7            ;          18h                                                                               ; 2-3-1 1st 64K RAM chip or data line failure - bit 8            ;          19h                                                                               ; 2-3-2 1st 64K RAM chip or data line failure - bit 9            ;          1Ah                                                                               ; 2-3-3 1st 64K RAM chip or data line failure - bit A            ;          1Bh                                                                               ; 2-3-4 1st 64K RAM chip or data line failure - bit B            ;          1Ch                                                                               ; 2-4-1 1st 64K RAM chip or data line failure - bit C            ;          1Dh                                                                               ; 2-4-2 1st 64K RAM chip or data line failure - bit D            ;          1Eh                                                                               ; 2-4-3 1st 64K RAM chip or data line failure - bit E            ;          1Fh                                                                               ; 2-4-4 1st 64K RAM chip or data line failure - bit F            E.sub.-- DMAS                                                                         EQU 20h                                                                               ; 3-1-1 slave DMA register test in-progress or failure           E.sub.-- DMAM                                                                         EQU 21h                                                                               ; 3-1-2 master DMA register test in-progress or failure          E.sub.-- PIC0                                                                         EQU 22h                                                                               ; 3-1-3 master interrupt mask register test in-progress or                     fail                                                             E.sub.-- PIC1                                                                         EQU 23h                                                                               ; 3-1-4 slave interrupt mask register test in-progress or                      fail                                                             E.sub.-- IVLD                                                                         EQU 25h                                                                               ;interrupt vector loading in-progress                            E.sub.-- KEYC                                                                         EQU 27h                                                                               ; 3-2-4 keyboard controller test in-progress or failure          E.sub.-- CVER                                                                         EQU 28h                                                                               ;CMOS power-fail and checksum checks in-progress                 E.sub.-- CCON                                                                         EQU 29h                                                                               ;CMOS config info validation in-progress                         E.sub.-- CRTM                                                                         EQU 2Bh                                                                               ; 3-3-4 screen memory test in-progress or failure                E.sub.-- CRTI                                                                         EQU 2Ch                                                                               ;3-4-1 screen initialization in-progress or failure              E.sub.-- CRTR                                                                         EQU2Dh ;3-4-2 screen retrace tests in-progress or failure               E.sub.-- VROM                                                                         EQU 2Eh                                                                               ;search for video ROM in-progress                                E.sub.-- OK                                                                           EQU 30h                                                                               ;screen believed operable:                                                30h  ;screen believed running w/video ROM                                      31h  ;monochromatic screen believed operable                                   32h  ;40-column color screen believed operable                                 33h  ;8column color screen believed operable                          E.sub.-- TIMRI                                                                          34h  ;4-2-1 timer tick interrupt test in progress or failure          E.sub.-- SHUTD                                                                        EQU 35h                                                                               ;4-2-1 shutdown test in.sub.-- progress or failure               E.sub.-- GTA20                                                                        EQU 36h                                                                               ;4-2-3 gate A20 failure                                          E.sub.-- PMUXI                                                                        EQU 37h                                                                               ;4-3-1 RAM test in.sub.-- progress or failure above address                    OFFFFh                                                           E.sub.-- TIMR2                                                                        EQU 3Ah                                                                               ;4-3-3 Interval timer channel 2 test in progress or                            failure                                                          E.sub.-- TODCK                                                                        EQU 3Bh                                                                               ;4-3-4 Time-of-Day clock test in.sub.-- progess or failure       E.sub.-- SRLPT                                                                        EQU 3Ch                                                                               ;4-4-1 Serial port test rest in.sub.-- progess or failure        E.sub.-- PRLPT                                                                        EQU 3Dh                                                                               ;4-4-2 Parallel port test test in.sub.-- progress or                           failure                                                          E.sub.-- 80287                                                                        EQU 3Eh                                                                               ;4-4-3 Math Coprocessor test in.sub.-- progess or failure        ;These are the values used for the Chip Set module HTSUMMIT HTK320             E.sub.-- CSINIT                                                                       EQU 050h                                                                              ;beginning of CSET.sub.-- INIT                                   E.sub.-- CSRCM                                                                        EQU 051h                                                                              ;beginning the RCM table                                         E.sub.-- CSDYN                                                                        EQU 052h                                                                              ;loading the FCM table, doing DMC                                E.sub.-- CSEP1                                                                        EQU 053h                                                                              ;entering CSET.sub.-- BFR.sub.-- VIDROM                          E.sub.-- CSEP2                                                                        EQU 054h                                                                              ;entering CSET.sub.-- BFR.sub.-- SIZMEN                          E.sub.-- CSEP3                                                                        EQU 055h                                                                              ;entering CSET.sub.-- AFT.sub.-- MTEST                           E.sub.-- CSEP4                                                                        EQU 056h                                                                              ;entering CSET.sub.-- AFT.sub.-- CMCFG                           E.sub.-- CSEP5                                                                        EQU 057h                                                                              ;entering CSET.sub.-- BFR.sub.-- OPROM                           E.sub.-- CSEP6                                                                        EQU 0h ;existing CSET.sub.-- BRR.sub.-- OPROM                           CGG103 Port 80 Codes and usage in Files                                        CHIPSET.ASM 379 9:                                                                          TREPORT E.sub.-- CSINIT                                                                     ;50 tell the diagnostic port where we are            CHIPSET.ASM 518 9:                                                                          TREPORT E.sub.-- CSRCM                                                                      ;51 Tell Port 80h where we are.                      CHIPSET.ASM 542 9:                                                                          TREPORT E.sub.-- CSDYN                                                                      ;51 Tell Port 80h where we are.                      CHIPSET.ASM 684 8:                                                                          TREPORT E.sub.-- CSEP1                                                                      ;53 tell the diagnostic port where we are.           CHIPSET.ASM 750 9:                                                                          TREPORT E.sub.-- CSEP2                                                                      ;54 tell the diagnostic port                         CHIPSET.ASM 767 9:                                                                          TREPORT E.sub.-- CSEP3                                                                      ;55 tell the diagnostic port where we are            CHIPSET.ASM 849 8:                                                                          TREPORT E.sub.-- CSEP4                                                                      ;56 tell the diagnostic port where we are            CHIPSET.ASM 896 8:                                                                          TREPORT E.sub.-- CSEP5                                                                      ;57 tell the diagnostic port where we are            CHIPSET.ASM 912 8:                                                                          TREPORT E.sub.-- CSEP6                                                                      ;0 tell the diagnostic port where we are             CHIPSET.ASM 1415 9:                                                                         TREPORT 0B0h ;b0                                                  CHIPSET.ASM 1427 9:                                                                         TREPORT 0Bh  ;b0                                                  CHIPSET.ASM 1439 9:                                                                         TREPORT 0B2  ;B2                                                  COMMSTES.ASM 177 9:                                                                         TREPORT E.sub.-- DMAS                                                                       ;20                                                  COMMSTES.ASM 197 9:                                                                         TREPORT E.sub.-- DMAN                                                                       ;21                                                  COMMSTES.ASM 227 9:                                                                         TREPORT E.sub.-- PIC0                                                                       ;22                                                  COMMSTES.ASM 242 9:                                                                         TREPORT E.sub.-- PICI                                                                       ;23                                                  COMMSTES.ASM 268 9:                                                                         TREPORT E.sub.-- IVLD                                                                       ;25                                                  COMMSTES.ASM 470 9:                                                                         TREPORT E.sub.-- KEYC                                                                       ;27                                                  COMMSTES.ASM 570 9:                                                                         TREPORT E.sub.-- CVER                                                                       ;28 announce test                                    CONFCHK.ASM 108 9:                                                                          TREPORT E.sub.-- TODCK                                                                      ;3B report start of test                             CONFCHK.ASM 208 9:                                                                          TREPORT E.sub.-- SRLPT                                                                      ;3C                                                  CONFCHK.ASM 252 9:                                                                          TREPORT E.sub.-- PRLPT                                                                      ;3D                                                  CONFCHK.ASM 291 9:                                                                          TREPORT E.sub.-- 80287                                                                      ;3E                                                  CONFCHK.ASM 494 9:                                                                          TREPORT 056h ;tell the diagnostic port where we are               CONFSCHK.ASM 525 10:                                                                        TREPORT 059h ;59 tell the diagnostic port where we are            CUSTINIT.ASM 108 9:                                                                         TREPORT E.sub.-- TIMRI                                                                      ;34                                                  CUSTINIT.ASM 169 9:                                                                         TREPORT E.sub.-- SHUTD                                                                      ;35 report shutdown test-in-prog                     CUSTINIT.ASM 454 9:                                                                         TREPORT E.sub.-- TIMR2                                                                      ;3A                                                  IOTESTS.ASM 86 9:                                                                           TREPORT E.sub.-- TIMR                                                                       ;04                                                  IOTESTS.ASM 226 9:                                                                          TREPORT E.sub.-- DMAI                                                                       ;05                                                  IOTESTS.ASM 320 9:                                                                          TREPORT E.sub.-- PAGE                                                                       ;06                                                  IOTESTS.ASM 392 9:                                                                          TREPORT E.sub.-- REFR                                                                       ;08                                                  IOTESTS.ASM 442 9:                                                                          TREPORT E.sub.-- RAM0                                                                       ;09                                                  KEYBOARD.ASM 875 9:                                                                         TREPORT E.sub.-- BAMEM                                                                      ;38                                                  MEMORY.ASM 272 9:                                                                           TREPORT E.sub.-- RAMP                                                                       ;0D                                                  POSTEXEC.ASM 202 9:                                                                         TREPORT 091h ;91                                                  POSTEXEC.ASM 291 9:                                                                         TREPORT E.sub.-- REGS                                                                       ;01                                                  POSTEXEC.ASM 401 9:                                                                         TREPORT E.sub.-- CRAM                                                                       ;02                                                  POSTEXEC.ASM 443 9:                                                                         TREPORT E.sub.-- BROM                                                                       ;03                                                  POSUBS.ASM 631 9:                                                                           TREPORT E.sub.-- CRTM                                                                       ;2B                                                  POSUBS.ASM 674 9:                                                                           TREPORT E.sub.-- CRTI                                                                       ;2C                                                  POSUBS.ASM 682 9:                                                                           TREPORT E.sub.-- CRTR                                                                       ;2D                                                  VIDSET.ASM 125 9:                                                                           TREPORT E.sub.-- CCON                                                                       ;29 check configuration                              VIDSET.ASM 301 9:                                                                           TREPORT E.sub.-- CRTI                                                                       ;2C                                                  VIDSET.ASM 407 9:                                                                           TREPORT E.sub.-- VROM                                                                       ;2E report the start of searching                    CSMACROS.INC 662 9:                                                                         TREPORT E.sub.-- CSDYN                                                                      ;52 Tell port 80h where we are                       PhoenixBIOS 4.0 (NuBlOS) Port 80 codes                                         TP.sub.-- VERIFY.sub.-- REAL                                                                  EQU 002h                                                        TP.sub.-- GET.sub.-- CPU.sub.-- TYPE                                                          EQU 004h                                                        TP.sub.-- HW.sub.-- INIT                                                                      EQU 006h                                                        TP.sub.-- CS.sub.-- INIT                                                                      EQU 008h                                                        TP.sub.-- SET.sub.-- IN.sub.-- POST                                                           EQU 009h                                                        TP.sub.-- CPU.sub.-- INIT                                                                     EQU 00Ah                                                        TP.sub.-- CACHE.sub.-- INIT                                                                   EQU 00Ch                                                        TP.sub.-- IO.sub.-- INIT                                                                      EQU 00Eh                                                        TP.sub.-- PM.sub.-- INIT                                                                      EQU 010h                                                        TP.sub.-- USERPATCH0                                                                          EQU 012h                                                        TP.sub.-- 8742.sub.-- INIT                                                                    EQU 014h                                                        TP.sub.-- CHECKSUM                                                                            EQU 016h                                                        TP.sub.-- TIMER.sub.-- INIT                                                                   EQU 018h                                                        TP.sub.-- DMA.sub.-- INIT                                                                     EQU 01Ah                                                        TP.sub.-- RESET.sub.-- PIC                                                                    EQU 01Ch                                                        TP.sub.-- REFRESH                                                                             EQU 020h                                                        TP.sub.-- 8742.sub.-- TEST                                                                    EQU 022h                                                        TP.sub.-- SET.sub.-- HUGH.sub.-- ES                                                           EQU 024h                                                        TP.sub.-- ENABLE.sub.-- A20                                                                   EQU 026h                                                        TP.sub.-- SIZE.sub.-- RAM                                                                     EQU 028h                                                        TP.sub.-- ZERO.sub.-- BASE                                                                    EQU 02Ah                                                        TP.sub.-- ADDR.sub.-- TEST                                                                    EQU 02Ch                                                        TP.sub.-- BASERAML                                                                            EQU 02Eh                                                        TP.sub.-- BASERAMH                                                                            EQU 030h                                                        TP.sub.-- COMPUTE.sub.-- SPEED                                                                EQU 032h                                                        TP.sub.-- CMOS.sub.-- TEST                                                                    EQU 034h                                                        TP.sub.-- CS.sub.-- RESUME                                                                    EQU 036h                                                        TP.sub.-- CS.sub.-- REINIT                                                                    EQU 037h                                                        TP.sub.-- SYS.sub.-- SHADOW                                                                   EQU 038h                                                        TP.sub.-- CACHE .sub.-- REINIT                                                                EQU 039h                                                        TP.sub.-- CACHE.sub.-- AUTO                                                                   EQU 03Ah                                                        TP.sub.-- ADV.sub.-- CS.sub.-- CONFIG                                                         EQU 03Ch                                                        TP.sub.-- READ.sub.-- HW                                                                      EQU 03Eh                                                        TP.sub.-- SPEED                                                                               EQU 040h                                                        TP.sub.-- VECTOR.sub.-- INIT                                                                  EQU 042h                                                        TP.sub.-- SET.sub.-- BIOS.sub.-- INT                                                          EQU 044h                                                        TP.sub.-- COPYRIGHT                                                                           EQU 046h                                                        TP.sub.-- CONFIG                                                                              EQU 048h                                                        TP.sub.-- PCI.sub.-- OP.sub.-- INIT                                                           EQU 047h                                                        TP.sub.-- PCI.sub.-- INIT                                                                     EQU 049h                                                        TP.sub.-- VIDEO                                                                               EQU 04Ah                                                        TP.sub.-- VID.sub.-- SHADOW                                                                   EQU 04Ch                                                        TP.sub.-- CR.sub.-- DISPLAY                                                                   EQU 04Eh                                                        TP.sub.-- CPU.sub.-- DISPLAY                                                                  EQU 050h                                                        TP.sub.-- KB.sub.-- TEST                                                                      EQU 052h                                                        TP.sub.-- KEY.sub.-- CLICK                                                                    EQU 054h                                                        TP.sub.-- ENABLE.sub.-- KB                                                                    EQU 056h                                                        TP.sub.-- HOT.sub.-- INT                                                                      EQU 058h                                                        TP.sub.-- DISPLAY.sub.-- F2                                                                   EQU 05Ah                                                        TP.sub.-- MEMORY.sub.-- TEST                                                                  EQU 05Ch                                                        TP.sub.-- BASE.sub.-- ADDR                                                                    EQU 05Eh                                                        TP.sub.-- EXT.sub.-- MEMORY                                                                   EQU 060h                                                        TP.sub.-- EXT.sub.-- ADDR                                                                     EQU 062h                                                        TP.sub.-- USERPATCH1                                                                          EQU 064h                                                        TP.sub.-- CACHE.sub.-- ADVNCD                                                                 EQU 066h                                                        TP.sub.-- CACHE.sub.-- CONFIG                                                                 EQU 058h                                                        TP.sub.-- DISP.sub.-- CACHE                                                                   EQU 06Ah                                                        TP.sub.-- DISP.sub.-- SHADOWS                                                                 EQU 06Ch                                                        TP.sub.-- DISP.sub.-- NONDISP                                                                 EQU 06Eh                                                        TP.sub.-- ERROR.sub.-- MSGS                                                                   EQU 070h                                                        TP.sub.-- TEST.sub.-- CONFIG                                                                  EQU 072h                                                        TP.sub.-- RTC.sub.-- TEST                                                                     EQU 074h                                                        TP.sub.-- KEYBOARD                                                                            EQU 076h                                                        TP.sub.-- KEYLOCK                                                                             EQU 07Ah                                                        TP.sub.-- HW.sub.-- INTS                                                                      EQU 07Ch                                                        TP.sub.-- COPROC                                                                              EQU 07Eh                                                        TP.sub.-- IO.sub.-- BEFORE                                                                    EQU 080h                                                        TP.sub.-- RS232                                                                               EQU 082h                                                        TP.sub.-- LPT  EQU 084h                                                        TP.sub.-- IO.sub.-- AFTER                                                                     EQU 086h                                                        TP.sub.-- BIOS.sub.-- INIT                                                                    EQU 088h                                                        TP.sub.-- INIT.sub.-- EXT.sub.-- BDA                                                          EQU 08Ah                                                        TP.sub.-- FLOPPY                                                                              EQU 08Ch                                                        TP.sub.-- AUTOTYPE                                                                            EQU 08Eh                                                        TP.sub.-- FDISK                                                                               EQU 090h                                                        TP.sub.-- FDISKLOCALBUS                                                                       EQU 091h                                                        TP.sub.-- USERPATCH2                                                                          EQU 092h                                                        TP.sub.-- DISABLE.sub.-- A20                                                                  EQU 094h                                                        TP.sub.-- CLEAR.sub.-- HUGH.sub.-- ES                                                         EQU 096h                                                        TP.sub.-- ROM.sub.-- SCAN                                                                     EQU 098h                                                        TP.sub.-- MISC.sub.-- SHADOW                                                                  EQU 09Ah                                                        TP.sub.-- PM.sub.-- SETUP                                                                     EQU 09Ch                                                        TP.sub.-- IROS EQU 09Eh                                                        TP.sub.-- TIME.sub.-- OF.sub.-- DAY                                                           EQU 0A0h                                                        TP.sub.-- KEYLOCK.sub.-- TEST                                                                 EQU 0A2h                                                        TP.sub.-- KEY.sub.-- RATE                                                                     EQU 0A4h                                                        TP.sub.-- ERASE.sub.-- F2                                                                     EQU 0A8h                                                        TP.sub.-- SCAN.sub.-- FOR.sub.-- F2                                                           EQU 0AAh                                                        TP.sub.-- SETUP.sub.-- CHECK                                                                  EQU 0ACh                                                        TP.sub.-- CLEAR.sub.-- BOOT                                                                   EQU 0AEh                                                        TP.sub.-- ERROR.sub.-- CHECK                                                                  EQU 0B0h                                                        TP.sub.-- POST.sub.-- DONE                                                                    EQU 0B2h                                                        TP.sub.-- ONE.sub.-- BEEP                                                                     EQU 0B4h                                                        TP.sub.-- PASSWORD                                                                            EQU 0B6h                                                        TP.sub.-- SYSTEM.sub.-- INIT                                                                  EQU 0B8h                                                        TP.sub.-- PARITY                                                                              EQU 0BCh                                                        TP.sub.-- CLEAR SCREEN                                                                        EQU 0BEh                                                        TP.sub.-- CHK.sub.-- RMDR                                                                     EQU 0BFh                                                        TP.sub.-- INT19                                                                               EQU 0C0h                                                        TP.sub.-- EXCEPTION                                                                           EQU 0D0h                                                        TP.sub.-- UNKNOWN.sub.-- INT                                                                  EQU OD2h                                                        TP.sub.-- PENDING.sub.-- INTS                                                                 EQU 0D4h                                                        TP.sub.-- SHUTDOWN.sub.-- 5                                                                   EQU 0D6h                                                        TP.sub.-- SHUTDOWN.sub.-- ERROR                                                               EQU 0D8h                                                        TP.sub.-- EBM  EQU 0DAh                                                        TP.sub.-- SHUTDOWN10                                                                          EQU 0DCh                                                        __________________________________________________________________________

                                      APPENDIX C                                   __________________________________________________________________________     MODIFICATIONS TO VARIOUS BIOS                                                  __________________________________________________________________________     A. Example PhoenixBIOS 1.03 (CBG103) Modifications                             1. Copy DEBUGCBG.ASM, the debug engine code (see FIGS. 3 and 4), to the        system BIOS directory.                                                         2. Modify the MAKEFILE to include DEBUGCBG.0BJ. Following is an example         of the Make file.                                                               objs2 =                                                                             casdsr.obj \                                                  xserv.obj \                                                          timdsr.obj                                                                               \                                                          opsubs.obj                                                                               \                                                          auxdsr.obj                                                                               \                                                          cmssub.obj                                                                               \                                                          prtscr.obj                                                                               \                                                          tables.obj                                                                               \                                                          peri.sub.-- all.obj                                                                      \                                                          filler.obj                                                                               \                                                          mod8k.obj \                                                          fls.sub.-- h4c.obj                                                                       \                                                          compas.obj                                                                               \                                                          debugcbg.obj                                                                   The following dependency line should be added to the Make file in              addition                                                                       to the above                                                                   debugcbg.obj                                                                              : debugcbg.asm $(INCS1)                                             3. Modify GENERIC.LNK to include DEBUGCBG, Add the DEBUGCBG after                FLS.sub.-- H4C file, before FILLR2:                                          CMSSUB, PRTSCR, CPU, FLS.sub.-- H4C,                                           DEBUGCBG, FILLR2, MOD8K, COMPAS                                                4. Modify the ROMOPT file to increase the codesize, if the size of the         BIOS                                                                             is larger than expected.                                                       The ROMOPT.INC usually is copied from *.opt file. Change code size and         ROM size to whatever size needed.                                            CODSIZ  EQU 42*1024                                                            ROMSIZ  EQU 48*1024                                                            5. Modify the COMPAS.ASM to add the debug engine default parameters as           shown in TABLE I above.                                                      6. Rename the TREPORT MACRO to ATREPORT. Add the following new                   Macro (near entry) to BIOS\MACROS.INC.                             TREPORT macro ERRCODE                                                          LOCAL   retAddr  ; Segment                                                     IFNDEF  NO.sub.-- EXTRN                                                        EXTRN    debugEngineNearEntry:NEAR                                             ENDIF                                                                          mov  dr3, eax    ; Save EAX in DR3                                             mov  al,ERRCODE                                                                lahf             ; Load the flags into AH                                      shl  eax, 16     ; Shift AX to higher word of EAX                              mov  ax, offset retAddr                                                                         ; Jump direct to the Debug Engine                             jmp  debugEngineNearEntry                                                      retAddr:                                                                       mov eax, dr3     ; Restore original EAX                                        ENDM                                                                           __________________________________________________________________________     EXAMPLE MODIFICATIONS FOR USE IN                                               POWER MANAGEMENT (Far Entry)                                                   __________________________________________________________________________     1. Modify \PM\MACROS.INC and replace DPORT and             DPORTNW macros with                                                               the following new Macro:                                                    DEBADDR EQU 0E3F0H                                                             DPORT macro ERRCODE                                                            LOCAL  retAddr                                                                 LOCAL  ret1                                                                    mov  dr3, eax ; Save EAX in DR3                                                lahf          ; Load the flags into AH                                         mov  al,ERRCODE                                                                              ; Save the Debug code in AL                                      shl  eax, 16  ; Shift AX to higher word of EAX                                 mov  ax, ds   ; Save DS in AX                                                  mov  dr2, eax ; DR2 = flags 8 bits,errcode 8 bits,DS                                         ; 16 bits                                                        mov  ax, 0F000H                                                                              ; Get the segment of the Debug Engine                            mov  ds, ax   ; Load it into DS                                                mov  ax, si   ; Save SI in the higher 16 bits of EAX                           shl  eax, 16  ; Get the Segment of current location of the                     mov  ax, cs   ; Macro & save it in lower word Save the SI in AX                mov  si, offset retAddr                                                                      ; Load offset of the return address                              jmp  dword ptr ds:[DEBADDR]                                                                       ; Jump indirect to the Debug Engine                         retAddr:                                                                            dw  offset Ret1                                                                           ; Offset of the next instr. to execute                              dw  0E800h ; Segment of the code the Macro will                           ret1:           ; be expanded in                                                    mov ds, ax ; Restore DS                                                        mov eax, dr1                                                                              ; DR1 contains the SI register                                      mov si, ax ; Restore SI                                                        mov eax, dr3                                                                              ; Restore EAX                                                  ENDM                                                                           DPORTNW macro ERRCODE                                                          LOCAL  retaddr                                                                 LOCAL  ret1                                                                    mov  dr3, eax ; Save EAX in DR3                                                lahf          ; Load the flags into AH                                         mov  al, errcode                                                                             ; Save the Debug code in AL                                      shl  eax, 16  ; Shift AX to higher word of EAX                                 mov  ax, ds   ; Save DS in AX                                                  mov  dr2, eax ; DR2 = flags 8 bits,effcode 8 bits,DS 16 bits                   mov  ax,0F000H                                                                               ; Get the segment of the Debug Engine                            mov  ds, ax   ; Load it into DS                                                mov  ax, si   ; Save SI in the higher 16 bits of EAX                           shl  eax, 16  ; Get the Segment of current location of the                     mov  ax, cs   ; Macro & save it in lower word Save the SI in AX                mov  si, offset Ret.sub.-- Addr                                                                ; Load offset of the return address                            jmp  dword ptr ds:[DEBADDR]                                                                       ; Jump indirect to the Debug Engine                         retAddr:                                                                            dw offset Ret1                                                                            ; Offset of the next instr. to execute                              dw 0E800h  ; Segment of the code the Macro will                           ret1:           ; be expanded in                                                    mov                                                                               ds, ax  ; Restore DS                                                        mov                                                                               eax, dr1                                                                               ; DR1 contains the SI register                                      mov                                                                               si, ax  ; Restore SI                                                        mov                                                                               eax, dr3                                                                               ; Restore EAX                                                  ENDM                                                                           NOTE: When passing the debug code, you can either pass it through AL or        Parameter to the Macro. For example:                                                    DPORT 040H or                                                                  DPORT AL                                                              B. Example PhoenixBIOS 4.0 (NuBIOS) Modifications                              1. Modify the BCP.ASM file at the OEM level to include your Debug Engine       Code                                                                           (see FIGS. 3 and 4) in the build.                                              Enter INSTALL.sub.-- DEBUG in this file.                                       2. Setup default parameters that are used by debug engine in the               BCPS.INC                                                                         file as in Table II above.                                                   3. There is a new Macro created for entering the debugger, this Macro is       already                                                                        added to the locations where the current TESTP Macro is used. In order to      add                                                                            additional debug points use the BREAK.sub.-- POINT Macro from where you        want to                                                                        call the debug engine.                                                         ;***********************PhoenixBIOS 4.0**********************************      .                                                                              ;Place the following in C:\NUBIOS\INCLUDE\GE     NERAL.INC file (Near Entry)                                                     TESTP   MACRO   testNUMBER                                                    LOCAL  retAddr                                                                 EXTERNDEF   debugEngineDispatch:NEAR                                           mov  dr3, eax   ;Save EAX in DR3                                               mov  al, testNumber                                                                            ;Shift AX to higher word of EAX                                lahf            ;load the flags into AH                                        shl  eax, 16    ;Shift AX to higher word of EAX                                mov  ax,offsetretAddr                                                                          ;Jump direct to the Debug Engine                               jmp  debugEngineDispatch                                                       retAddr:                                                                       mov  eax,dr3    ;Restore original EAX                                          ENDM                                                                           ;These modification should be done in C:/CORE/STD/DEV/UTILS.ASM file           EXTERNDEF     debugEngineNearEntryRet:NEAR                                     EXTERN        debugEngineNearEngine (debugEngineNear                           EntryRet):NEAR                                                                 debugEngineDispatch:                                                           jmp  DebugEngineNearEntry                                                                       ; If debugEngine linled.sub.-- in, go there                   DebugEngineNearEntryRet:                                                       mov  dr2, eax                                                                  shr  eax, 16                                                                   out  TEST.sub.-- PORT, al                                                      sahf                                                                           mov  eax, dr2                                                                  jmp  ax       ; jump back to the debug macro that jumped to us                 ; in C:\NUBIOS\INCLUDE\BCPS.INC, add or          replace the following                                                          INSTALL.sub.-- DEBUG MACRO                                                     biosSegment SEGMENT                                                            EXTERN  debugEngineNearEntry:NEAR                                              biosSegment ENDS                                                               ENDM                                                                           ;-------------------------------------------------------------------------     -----------------                                                              ; Macro for PhoenixBIOS 4.0 (NuBIOS) debug engine, Far Entry                   ;-------------------------------------------------------------------------     -----------------                                                              DEBADDR   EQU 0E3F0H                                                           BREAK.sub.-- POINT.sub.-- FAR MACRO ERRCODE                                    LOCAL  pmRetAddr                                                               LOCAL  pmRetOffset                                                             LOCAL  pmDebugRetSegment                                                       mov  dr3, eax   ; Save EAX in DR3                                              lahf            ; Load the flags into AH                                       mov  al,ERRCODE ; Save the Debug code in AL                                    shl  eax, 16    ; Shift AX to higher word of EAX                               mov  ax, ds     ; Save DS in AX                                                mov  dr2, eax   ; DR2 = flags 8 bits,errcode 8 bits,DS 16 bits                 mov  ax, BIOSCODESEG                                                                           ; Get the segment of the Debug Engine                          mov  ds, ax     ; Load it into DS                                              mov  ax, si     ; Save SI in the higher 16 bits of EAX                         shl  eax, 16    ; Get the Segment of current location                          mov  ax, cs     ; of the Macro & save it in lower word                         mov  WORD PTR cs:[pmDebugRetSegment], ax                                                       ; save the SI in AX                                            mov  si, OFFSET pmRetOffset                                                                       ; Load offset of the return address                         jmp  dword ptr ds:[DEBADDR]                                                                       ; Jump indirect to the Debug Engine                         pmRetOffset:                                                                   DW   OFFSET pmRetAddr                                                                          ; Offset of the next instr. to execute                         pmDebugRetSegment:                                                                             ; This label is used in pminit.asm                             DW   0          ; to set the smram segment                                     pmRetAddr:                                                                     mov  ds, ax     ; Restore DS                                                   mov  eax, dr1   ; DR1 contains the SI register                                 mov  si, ax     ; Restore SI                                                   mov  eax, dr3   ; Restore EAX                                                  ENDM                                                                           __________________________________________________________________________ 

We claim:
 1. In a development computing system having a processor and a memory with an interrupt-handling portion, a computer-implemented method for processing debug codes in the development system, the method comprising the steps of:receiving, at a host computer operatively coupled to the development computing system, a debug code generated by the development computing system for processing by the processor; and directing the debug code from the host computer to a debug program located in the interrupt-handling portion of the memory of the development computing system.
 2. The computer-implemented method of claim 1 wherein the debug code comprises a port 80 code.
 3. The computer-implemented method of claim 1 wherein the debug code comprises a beep code.
 4. The computer-implemented method of claim 1 wherein the debug code is directed to the debug program according to an entry program located in the interrupt-handling portion of the memory.
 5. The computer-implemented method of claim 4 wherein the debug program corresponds to a memory location and the entry program provides the memory location.
 6. The computer-implemented method of claim 4 wherein the debug program corresponds to a memory offset and the entry program provides the memory offset.
 7. The computer-implemented method of claim 4 wherein the debug program corresponds to a segment and offset in memory and the entry program provides the segment and offset.
 8. The computer-implemented method of claim 1 wherein the memory comprises read only memory (ROM).
 9. The computer-implemented method of claim 1 wherein the interrupt-handling portion of the memory comprises a basic input/output system (BIOS).
 10. The computer-implemented method of claim 1 wherein the interrupt-handling portion of the memory is in a ROM BIOS computer chip.
 11. The computer-implemented method of claim 1 further comprising the step of:directing the debug code to a host computer for debugging the development system, wherein the debug program directs the debug code to the host computer via a communication channel in the development system.
 12. The computer-implemented method of claim 11 wherein the communication channel comprises a bi-directional parallel port in the development system.
 13. The computer-implemented method of claim 11 wherein the communication channel comprises a serial port in the development system.
 14. The computer-implemented method of claim 11 further comprising step of:saving the contents of registers in the development system on the host computer via the communication channel.
 15. The computer-implemented method of claim 14 further comprising step of:restoring the contents of the registers in the development system from the host computer to the development system via the communication channel.
 16. The computer-implemented method of claim 11 further comprising steps of:receiving a debug command for processing by the processor in accordance with instructions in the debug program, wherein the debug command is received from the host computer via the communications channel.
 17. The computer-implemented method of claim 16 further comprising steps of:executing the debug command on the processor in accordance with instructions in the debug program.
 18. The computer-implemented method of claim 17 further comprising steps of:sending information associated with the development system to the host computer from the development system via the communication channel in response to execution of the debug command.
 19. In a development computing system having a processor and a memory with an interrupt-handling portion, a computer-implemented method for debugging the development system, the method comprising the steps of:receiving a debug command from a host computer via a communications channel; directing the debug command to a debug program located in the interrupt-handling portion of memory; executing the debug command on the processor in accordance with instructions in the debug program; and sending information associated with the development system to the host computer from the development system via the communication channel in response to execution of the debug command.
 20. The computer-implemented method of claim 19 further comprising the steps of:saving the contents of registers in the development system on the host computer via the communication channel; and restoring the contents of the registers in the development system from the host computer to the development system via the communication channel.
 21. A system for debugging a development computing system, the system comprising:a processor in the development system, for executing program instructions; a communication channel, coupled to the processor, for sending and receiving data; a host computer, communicatively coupled to the processor via the communication channel; and memory in the development system, coupled to the processor, for storing instructions for execution by the processor, wherein the memory comprises an interrupt-handling module of program instructions executable on the processor for handling interrupts issued by the development system, and wherein the interrupt-handling module of memory further comprises a debug module of program instructions executable on the processor for receiving interrupt information and for sending such information to the host computer via the communication channel.
 22. The system of claim 21 wherein the communication channel comprises a bi-directional parallel port in the development system.
 23. The system of claim 21 wherein the communication channel comprises a serial port in the development system.
 24. The system of claim 21 wherein the host computer comprises debug software, and the host computer sends a debug command to the development system via the communication channel.
 25. The system of claim 24 wherein the processor in the development system executes the debug command on the processor according to program instructions in the debug module of memory.
 26. The system in claim 25 wherein data associated with the development system is sent to the host computer via the communication channel in response to the execution of the debug command.
 27. The system in claim 21 wherein the memory comprises read only memory (ROM).
 28. The system of claim 21 wherein the interrupt-handling module comprises a basic input/output system (BIOS).
 29. The system of claim 21 wherein the interrupt-handling module is in a ROM BIOS computer chip.
 30. The system of claim 21 wherein the development system further comprises at least one register having contents that are saved on the host computer via the communication channel according to program instructions in the debug module.
 31. The system of claim 30 wherein the contents of said register are restored to the development system from the host computer via the communication channel according to the program instructions in the debug module.
 32. The system of claim 21 wherein the interrupt-handling module comprises an entry module of program instructions executable on the processor for directing the interrupt information to the debug module.
 33. The system of claim 21 wherein the interrupt information comprises a port 80 code.
 34. The system of claim 21 wherein the interrupt information comprises a beep code. 